Conventionally known information storage apparatus which are incorporated in or connected to electronic equipment such as personal computers and word processors include hard disk drives which magnetically record information on magnetic disks (hard disks) and MO disk drives which optically and magnetically record information on magneto-optical (MO) disks.
Generally, a hard disk drive is equipped with a magnetic disk which serves as an information recording medium and a head which reads and writes recorded bits from/to the magnetic disk as well as with a slider which carries the head, suspension and arm which bring the slider close to the magnetic disk and hold it, and actuator which moves the head along the magnetic disk by driving the suspension and arm.
The recording density of the hard disk drive has been growing along with the development of the personal computer and the like. Especially, with the recent rise in demand for personal computers and the like to handle images and music, the recording density has grown dramatically. The growth in the recording density of the hard disk drive in turn has resulted in finer recorded bits on the magnetic disk and higher rotational speed of the magnetic disk. Consequently, there is growing demand for higher accuracy and higher speed of head positioning. Also, there is strong demand for ease of manufacture as well as for downsizing.
In response to these demands, techniques have been proposed which increase the accuracy and speed of head positioning by adding a twist to details of the arm and suspension of the hard disk drive. For example, patent documents 1 and 2 describe a technique for reducing vibrations caused by external forces by bending edges of a leaf-spring-like suspension which holds a slider. Also, patent document 3 describes a technique which employs a lead consisting of multiple wires laid on a metal sheet as a lead-in wire (lead) instead of a wire lead consisting of separate lead wires. Also, patent document 3 proposes that the lead should be integrated with the arm.
Patent document 1
Japanese Patent Laid-Open No. 62-279570
Patent document 2
Japanese Patent Laid-Open No. 1-177473
Patent document 3
Japanese Patent Laid-Open No. 10-116409
Incidentally, to attach a lead consisting of multiple wires laid on a metal sheet to an arm, possible methods include fixing the lead to a projection overhanging from a flank of the arm, fixing the lead along the top and bottom faces of the arm, and fixing the lead along a flank of the arm by bending the lead in the middle.
With the method of fixing the arm to an overhanging projection, it is unadvisable to form the projection on the entire area of an arm flank because this will increase the inertia for an actuator, resulting in equipment performance degradation. Thus, the projection will be provided only on part of the arm flank. In that case, however, that part of the long lead which is not fixed to the projection will vibrate due to disturbance such as air flow caused by the rotation of the magnetic disk, and acceleration or shocks caused by arm movements (seeks), adversely affecting the positioning accuracy of the head.
With the method of fixing the lead along the top and bottom faces of the arm, clearance between the arm and magnetic disk is reduced at least by the amount equivalent to the thickness of a tail. This increases the possibility that the arm will touch the magnetic disk if the arm bends due to a shock, and thus decreases equipment reliability. To avoid decreasing equipment reliability, the clearance between the arm and magnetic disk must be increased, but this runs counter to downsizing of the equipment.
With the method of fixing the lead along a flank of the arm by bending the lead in the middle, it is difficult to provide a sufficient bending accuracy. Bending error can cause misalignment in the end of the lead at the root of the arm, hindering connection with an FPC (Flexible Printed Circuit) provided at the root of the arm.
On the other hand, the method of integrating the lead with the arm poses a problem of poor manufacturability.